Optical modulation of nanoporous alumina anodic oxide thin film on sapphire by the superparamagnetic from nano patterns upon

The optical behavior of nanoporous alumina anodic oxide thin film (AAOF) on sapphires can be modulated with varying the nanopore diameters. The excited photoluminescence spectrum splits into two wavelengths of near blue and green peaks. This light modulation could relate to the superparamagnetic magnetization of the patterns upon in nanoscale. With increasing the nanopore size by reaming method, the superparamagnetic susceptibility decreases firstly and then increased. When the superparamagnetic susceptibility deviates from that of the as-received, the excited green peak arises. On the other hand, strong superparamagnetic facilitates the excitation of blue peak.